This invention relates to gas extraction.
The invention is concerned especially with extraction of waste gas in the context of general anaesthesia. In general anaesthesia there is danger of the anaesthetist and others attending on the human or animal patient, being themselves affected by the gas administered. This danger can arise from leakage occurring from the mask or other means used to administer the gas, and also from residual gas expired by the patient.
The adverse effects on the health and performance of anaesthetists and others exposed in their work to anaesthetic gases has been recognised for many years, and proposals involving shields have been made for reducing these effects. In particular, proposals have been made for extracting gas from around the patient's mouth and nose, and for shielding the one or more attendants located nearby, using a generally-flat transparent screen between them and the patient. Such proposals, however, have been found generally unsatisfactory owing to the obstructive nature and general inefficiency of the extraction equipment and shielding.
It is one of the objects of the present invention to provide gas-extraction equipment and methods that may be used with advantage over known gas-extraction equipment and methods, in the context of general anaesthesia.